Temporal and spatial structure of a runaway electron beam in air at atmospheric pressure.

The time- and spatial structure of a runaway electron beam generated in air at atmospheric pressure by a high-voltage pulse with a rise time of ∼300 ps is studied experimentally and numerically. It is obtained that the duration of the runaway electron current is a few tens of picoseconds, and it can consist of two or many peaks. It is shown that the many-peak temporal structure of the beam is caused by the non-simultaneous appearance of several emission centers on the cathode edge. [ABSTRACT FROM AUTHOR]